I. Field of the Invention
This invention relates generally to electrosurgical apparatus and more particularly to a bipolar electrosurgical instrument which may be routed through an endoscope or similar device such as a resectoscope, a laparoscope or videoscope, and especially adapted for resecting tumors and the like from body organs accessible through such a device.
II. Discussion of the Prior Art
Electrosurgery has become a widely adopted procedure for treating a wide variety of medical problems. This type of surgery offers the advantage of not only readily cutting tissue but also effecting hemostasis through cauterization. In monopolar electrosurgery, a high frequency RF generator has its outputs connected between a large area skin-contacting body electrode and the blade or wire used to effect cutting. The body electrode is remote from the active cutting electrode and currents flow through generally indeterminate paths back to the body electrode. In bipolar electrosurgery, the active or cutting electrode and the return electrode are generally closely spaced to one another such that the return currents are confined to the tissue positioned between the active electrode and the return electrode on the instrument. Generally speaking, then, improved control during the surgical procedure can be achieved using bipolar electrosurgical techniques.
The Morrison Pat. No. 4,043,342 describes a bipolar electrosurgical device in which the active electrode comprises a needle and the return electrode a rigid, inflexible cap through which the needle electrode passes in an insulating fashion. This device is primarily intended as a hand-held electrosurgical scalpel which does not lend itself to surgical procedures except those that can be reached through a body incision. It is oftentimes desirable to effect a surgical procedure in a location accessible through an existing body orifice. For example, patients suffering from esophageal cancer may develop tumors which grow to a size where they can effectively block the esophagus, preventing food from passing to the stomach. The blockage problem can oftentimes be resolved by resecting the tumor by an instrument which may be fitted through the lumen of an endoscope or videoscope whereby the physician can view the surgical site.
In yet another instance, bladder tumors may be resected by first passing a endoscope through the urethra and into the bladder. However, a suitable instrument is then needed to reach those locations within the bladder where the tumors may be present. Until now, there has not been an electrosurgical instrument that can effectively be used to resection tumors using an endoscope to gain access to the surgical site. The present invention provides such an instrument.